The Patriot Act, instead of its stated intention of preventing terrorism, has instead caused Americans to doubt their government. Their doubt includes both the government's ability to handle terrorism as well as the government's respect for the privacy and rights of its citizens. When the country is threatened by both war and terrorism, it is especially important to have the support of its citizenry.
The Patriot Act is not only ineffective, but has allowed massive intrusion into our private lives, which ultimately violates civil rights guaranteed by the Constitution. There is little or no evidence that the Patriot Act has done anything to protect the US from terrorists (it's original intent). It has, however, resulted in massive abuses, such as the NSA's gathering of private data from American citizens. It has also resulted in people being imprisoned, and held more or less indefinitely, without the necessity of charges being filed against them, blatantly violating the Constitution.